Ensure test_command tests are actually correct

Using
```
assert 'changed' in result
```
doesn't actually check if something is changed, which is presumably
the reason for the assertion. What is actually needed is
```
assert result.get('changed')
```
which checks that changed is set and not False. Tests still pass after
this change
Merge pull request #5137 from willthames/test_runner_fix

Ensure test_command tests are actually correct